The present invention relates to a method and apparatus for cutting a predetermined length of insulation batt in a manner that leaves an exposed length of backing material which can be used to assist in installing the length of insulation batting.
One type of insulating material used in building structures and the like is typically supplied in rolls of various diameters, such rolls being formed from rolled up, elongated lengths of insulation batting which comprises a sheet of an insulating material such as fiberglass fibers that is several inches thick, with one face of the fiberglass fiber sheet being adhered to a backing of aluminum covered paper or the like of substantially less thickness.
It is frequently desirable to use such insulating material to enhance the heat transfer characteristics of the individual duct lengths of a heating and cooling system of a structure such as a building so that the heated and/or cooled air moving therethrough is not disadvantageously dissipated during its passage through the ducts. To this end, one practice for enhancing the heat transfer characteristics of the duct lengths involves encircling the outer circumferential surface of the duct lengths with conventional insulating materials, such as the insulation batting to improve the heat transfer characteristics of the duct lengths. The insulation batting is particularly suitable for efficient and dependable installation on the duct lengths since it comprises an effective insulating medium of several inches thickness of relatively loosely intertwined fiberglass fibers adhered to an aluminum covered backing and this combination of the fiberglass fibers and a relatively smooth, easily graspable backing is a product particularly suited for handling, cutting and securing in discrete, readily assemblable lengths.
Insulation installers usually follow either a simple procedure or a slightly more time consuming second procedure for installing the insulation on the ductwork. The simple procedure involves unrolling a length of insulation batting from a commercially available roll of insulation batting material to obtain an unrolled length of insulation batting slightly greater than the circumference of the duct to be insulated, severing the insulation length from the roll of insulation and installing the severed length in encircling disposition about the duct. Since the insulation length is slightly greater than the circumference of the duct, the edge portions thereof which extend axially along the duct length slightly overlap one another, thereby providing an area through which staples or the like can be driven to permanently secure the insulation length in its encircling dispostion about the duct length. While this simple procedure permits relatively rapid installation of the insulation lengths on the duct lengths, the overlapped edge portions of the duct insulation pieces tend to create a relatively bulky, non-uniform seam because the overlapped portion has a thickness roughly twice that of the rest of the insulation length. For this reason, insulation installers have developed a second installation procedure which, although relatively more time consuming than the simple procedure described above, tends to provide a more uniform, more easily securable seam. In this second procedure, once the insulation length has been severed from the insulation roll using a hand-held knife, the insulation installer uses the same knife to cut through the insulation length sufficiently to completely cut through the thickness of fiberglass fibers, but not into the aluminum covered backing, along a cutting line generally parallel to, and spaced several inches inwardly from, one of the severed edges of the insulation length. Thereafter, the insulation installer manually removes the band of fiberglass fibers between that cutting line and the severed edge to expose the inside surface of the aluminum covered backing along a generally elongate rectangular strip, and the removed fiberglass fibers are discarded. The thus prepared insulation length is then disposed in encircling disposition on the duct length and the remaining fiberglass fiber thickness of the insulation piece, which now is approximately equal to the circumference of the duct length, is disposed in facing contact with the outer circumferential surface of the duct length. Since the strip of exposed aluminum covered backing overlaps the adjacent aluminum covered backing adjacent the other overlapping edge, the installation installer can then drive staples through the strip of exposed aluminum covered backing into the overlapped aluminum covered backing and fiberglass fibers therebelow to secure the insulation length in permanent encircling disposition about the duct length.
While providing a more uniform and securable seam, the second insulation length preparation procedure is time consuming and requires that the installer have the skill to exert a relatively high degree of care during cutting of the fiberglass fibers to avoid penetrating the aluminum covered backing. Moreover, to achieve a cutting line sufficiently parallel to the adjacent edge of the fiberglass fiber thickness, the insulation installer must typically use a straight edge member such as a ruler, thus adding to the insulation length preparation time and the difficulty of the operation. Finally, this procedure requires increased handling and manipulating of the insulation, which is undesirable because of the known abrasive characteristics of fiberglass and similar insulating materials.